Assuming you want a DVD that actually plays in a standard DVD player you'll probably want 720 × 576 for PAL TV countries (Australia, Europe etc) or 720 × 480 for NTSC countries (USA) so you're going to lose pixels. If you're a Windows user Movie Maker is a simple way to do it.

Otherwise you could re-encode using something like H.264 and drop the bit rate to keep the resolution but maybe at a bit of a drop in quality, but that's not going to play on a lot of devices so probably isn't a good format to hand out to people.